Field PA1 State of the Art
The invention is in the field of projection equipment for controlling the projection of an image in a sports simulation game and for projecting a spot of light superimposed on the image which simulates the travel of an object through the image such as the travel of a golf ball in an image of a golf course projected on a screen.
Various arrangements are used for simulating the playing of a game of golf in small areas, such as indoors, to provide opportunities for people to play who might not otherwise be able to play because of crowded golf course conditions or because of bad weather. In addition, such golf simulators can simulate play on various famous golf courses not otherwise accessible to the players.
Most golf simulation equipment includes at least three components: a central control unit which keeps track of play and calculates ball travel and lie, a sensor unit which senses how a ball is hit to enable the control unit to calculate the trajectory and resulting lie of the hit ball, and a projection unit for projecting an image showing the green to which the ball is to be hit from the location of the ball. Because the equipment senses how a ball is hit and the distance and direction of travel of the ball, such equipment could also be adapted to simulate various other sport games, such as baseball or soccer, or at least various practice aspects thereof.
U.S. Pat. Nos. 4,150,825 and 4,437,672 show a type of golf simulation game. In the game of the patents, one to four players initially enter information into the control unit regarding the players and the men's, women's, or championship tees from which each will play, and the particular course and holes to be played, e.g., the front nine, back nine, etc. The control unit then operates a display to show who is to tee off and operates a projector to project an image on a screen in front of the players showing the view toward the green from the tee. The designated player hits his or her ball from the tee toward the green as he or she would on a regular golf course, the ball flying toward and hitting the screen which is specially designed for that purpose and is usually located about twenty feet in front of the player. Special sensors in the form of photosensor arrays are arranged to detect passage of the ball through three separate sensing planes, the third plane being positioned with respect to the screen so as to sense the ball's movement toward the screen and also the ball's rebound from the screen. With the information from the sensors, the ball's trajectory can be calculated and the position at which the ball lands along the fairway can be determined relatively accurately. The control unit keeps track of each player's ball and the position at which it landed. After all players have teed off, the control unit determines which player's ball is farthest from the hole and causes operation of the projector to move to and project an image on the screen showing the view from the position of the farthest ball looking toward the green. The player again hits his or her ball toward the green shown on the screen and again the trajectory of the ball is calculated and the new position along the fairway determined. The control unit then again determines the farthest ball from the hole, displays the name of the player, and instructs the projector to provide the new appropriate image. The identified player then hits his or her ball. Play is continued in this manner until all players reach the green. At that time, a simulated green is lighted and the players actually putt the ball into a hole in the simulated green.
In order to fully simulate the game, it is necessary to provide a representation of the ball traveling down the fairway toward the green so that players can watch the ball as it travels as they would do in a real game. Thus, ball projecting apparatus in the form of light spot projectors which project a small spot of light onto the screen to simulate the hit ball have been added to the equipment shown in the referenced patents. The light spot projector used with such equipment is aligned with the projector projecting the image of the golf course and moves the light spot to correspond with the calculated trajectory of the travel of the ball.
The prior art light spot projector utilizes two mirrors, each controlled by a separate stepper motor to provide the vertical and horizontal deflections, respectively, of a light spot on the screen. However, since the light spot projector is located near the image projector, both about twenty feet from the screen, very small movements of the mirrors projecting the light spot cause large movements of the light spot. Further, uneven movements or stepping of the mirrors causes unrealistic, uneven jumping of the light spot. The prior art projectors used mechanical stops to determine the home reference or starting positions of the mirrors, which, because of the characteristics of the stepper motors and their step controls, were not accurate in providing the same starting position from unit to unit and were very difficult to adjust.
While the light spot projectors add greatly to the simulation of a game, improvements in the control of the light spot to provide a smooth, accurate movement representative of the trajectory of the ball are desirable.